can I program a different operating system into a gen 3 pcm?? I have a pcm service number 12586243 from a 03 express that I want to use in my 95 f body but that pinout has no tach output. can I program a different operating system from a 03 Silverado pcm with a different service number 12576106 both pcms have different hardware numbers also but both are 58x and use blue / green connectors